Sedro-Woolley to Horse Ranch 230 kV transmission line

Fall 2010 project completion

Project overview

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Puget Sound Energy installed a new 230 kilovolt transmission line and fiber-optic line along 40 miles of our transmission line corridor between our Sedro-Woolley substation and our Horse Ranch substation, which is located in Lake Stevens. We upgraded our existing 115 kV transmission lines, which were on wooden H-frame structures, with a new 230 kV transmission line on mono pole structures. In addition, PSE upgraded Sedro-Woolley and Horse Ranch substations to accommodate the new line. Our new transmission and related fiber-optic lines increase capacity and improve reliability of the system.

Fiber-optic lines help PSE monitor and coordinate our electric transmission system remotely through instantaneous communication. Before the new fiber-optic line was installed, PSE managed the existing transmission line through static data points, which require manual manipulation of switches to operate the system—a utility worker had to physically go out to the line to flip the switches. With the fiber-optic line, PSE has the ability to flip the switches from a remote control room. The new transmission line will help mitigate power outages, and support future growth in the area.

What is a transmission line?

Transmission lines are key elements in the electrical distribution system. The lines safely transport high voltage electricity from power generation sources like dams and wind generating facilities to substations in local communities. Transmission normally takes place at voltages of 55 kV and higher.

What is a fiber-optic line?

A fiber-optic line or optical fiber is a glass fiber that is designed to direct light along its length and is used for communication purposes. The fiber-optic lines used in our electric system are small, half-inch in diameter lines. Fiber-optic is light, less expensive, and able to carry much more information than radio and microwave communication.

Committed to keeping you informed

PSE will continue to provide updates to the community. We will notify residents and businesses near the project area when construction will occur. We aim to complete the work with as little disruption as possible.